Absorbent products such as sanitary napkins and diapers typically comprise an absorbent core, a liquid impermeable backing material, and a liquid permeable facing material. The impermeable backing material prevents the bodily fluid from seeping out from the absorbent core and staining the wearer's clothing. The absorbent core is also covered with a facing material that, inter alia, also serves to contain the absorbent core.
Normally, absorbent articles, such as pantyliners, sanitary napkins, baby and adult diapers, as well as other adult incontinence devices, are formed by securing a liquid impermeable film to an absorbent core and then attaching a facing material to the impermeable film thereby securing the absorbent core between these two layers. See, e.g., Datta, et al., U.S. Pat. No. 4,892,534, the disclosures of which are herein incorporated by reference in their entirety. This process is both time consuming and expensive. Moreover, if the facing is not in intimate contact with the core, the liquid on the surface of the facing will puddle up and not penetrate through the facing but rather run off the surface. This is highly undesirable behavior.
It is also undesirable to have the absorbent products move during use. The attachment systems presently available often fail in this regard. During storage, the attachment system's adhesive is covered with a release liner. Polyethylene or silicone coated polyethylene paper is frequently used on the liners. Current adhesive attachment systems consist of continuous coating of pressure-sensitive adhesives and a continuous silicone coating on a release liner. Adhesives are normally thermoplastic rubber based and hot melt coated, and are typically plasticized with oil. For various reasons, the oil is an undesirable component of the adhesive. It imparts poor holding properties to the adhesive and tends to move in the system by migrating from the adhesive to the film, which is quite undesirable. The release liner on the attachment adhesive is normally silicone or polyethylene coated paper. The resulting surface finish of silicone coated papers is super smooth and the adhesive contact is 100% with the release surface, which can be problematic. Depending on the type of silicone coating, the silicone release system may cause the adhesive to be too easily released or too difficult to release, which is undesirable. Thus, it is important that the release paper have optimum release properties and at the same time make effective contact with the adhesive.
Many absorbent products optionally contain liquid absorbers, or odor absorbing materials to mask the potential odor associated with the excreted bodily fluids. It has been very difficult to immobilize such absorbents in disposable products. Frequently the powder moves, which is very undesirable. In the past powders have been immobilized on foams, or on continually coated pressure-sensitive adhesive surfaces to adhere absorbent powder, and then inserted into the absorbent product. However, these approaches are expensive because a great quantity of adhesive is required for immobilizing such materials.
Despite the advances that have been made in the field of absorbent products such as sanitary napkins, pantyliners, diapers, and incontinence products, there are still needs to be addressed. For example, there is a need for absorbent products that have better liquid transport properties and better odor and liquid absorbing properties. There is a further need for absorbent products with more effective attachment systems to give the user more security that the product will remain in place during routine use. There is also a need for absorbent products that are manufactured using less expensive and more efficient techniques. The present invention addresses these, as well as other needs in the art.